How a wave is formed. Formation of sea waves

The first multicellular organisms on Earth were sponges leading an attached lifestyle. However, some scientists classify them as complex colonies of protozoa.

general description

Sponges are a separate phylum in the animal kingdom with about 8,000 species.
There are three classes:

• Lime - have a calcareous skeleton;
• glass - have a silicon skeleton;
• Ordinary - have a silicon skeleton with spongin filaments (spongin protein holds parts of the skeleton together).

Rice. 1. Colony of sponges.

The general characteristics of the sponges are given in the table.

sign	Description
Lifestyle	Attached. They form colonies. Solitary representatives meet
habitats	Fresh and salt water bodies in different climatic zones
	Can reach 1 meter in height
	Heterotrophic. They are filter feeders. Internal flagella create a current of water penetrating into the body. Organic particles settled on the walls, plankton, detritus are absorbed by cells
reproduction	Sexual or asexual. During sexual reproduction, they lay eggs or form larvae. There are hermaphrodites. When asexual, they form buds or reproduce by fragmentation
Lifespan	Depending on the species, they can live from several months to several hundred years.
natural enemies	Turtles, fish, gastropods, starfish. Poison and needles are used for protection
Relationships	Can form symbiosis with algae, fungi, ciliary worms, mollusks, crustaceans, fish and other aquatic life

The main representatives of sponges are the cup of Neptune, the badyaga, the basket of Venus, the luminous sponge of klion.

Rice. 2. Klion.

Structure

Despite the fact that these are symmetrical animals with all the signs of a living organism, they are conditionally referred to as multicellular organisms, because. they do not have specific tissues and organs.

The structure of sponges is primitive, limited to two layers of cells permeated with pores and a skeleton. Visually, the sponges look like bags attached to the substrate with a sole. The walls of the sponge form the atrial cavity. The outer opening is called the mouth (osculum).
Separate two layers , between which there is a jelly-like substance - mesoglea:

• ectoderm - outer layer formed by pinacocytes - flat cells resembling epithelium;
• endoderm - the inner layer formed by choanocytes - cells resembling funnels with flagella.

The mesoglea contains:

• mobile amoebocytes that digest food and regenerate the body;
• sex cells;
• supporting cells containing spicules - silicon, limestone or horn needles.

Rice. 3. Structure of sponges.

Sponge cells are formed from undifferentiated cells - archeocytes.

Physiology

Despite the absence of organ systems, sponges are capable of nutrition, respiration, reproduction, and excretion. The receipt of oxygen, food and the release of carbon dioxide and other metabolic products occurs due to the inward flow of water, which is created by oscillations of the flagella.

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In the same way, fertilization occurs during sexual reproduction. With the flow of water, the spermatozoa of one sponge are absorbed, which fertilize the eggs in the body of another sponge. As a result, larvae are formed that come out. Some species produce eggs. They attach to the substrate and as they grow, they turn into an adult.

Every five seconds, a volume of water passes through the sponge equal to the internal volume of its body. Water enters through the pores, exits through the mouth.

Meaning

For humans, the meaning of sponges lies in the use of a solid skeleton for industrial, medical and aesthetic purposes. The ground skeleton was used as an abrasive and for washing. Soft-skeletal sponges were used to filter water.

Currently, dried and crushed badyaga is used in folk medicine for the treatment of bruises and rheumatism.

In nature, sponges are natural water purifiers. Their disappearance leads to water pollution.

What have we learned?

From the report for the 7th grade biology lesson, we learned about the features of the lifestyle, structure, meaning, nutrition, and reproduction of sponges. These are primitive multicellular animals that lead an attached lifestyle and are formed by two layers of cells. They filter water, getting food, oxygen and germ cells from it for fertilization. Metabolic products, spermatozoa and fertilized cells or larvae enter the water. Due to rapid regeneration, they are able to reproduce by fragmentation.

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The structure and classes of sponges

Sponges are ancient primitive multicellular animals. They live in marine, less often fresh water bodies. They lead a fixed lifestyle. They are filter feeders. Most species form colonies. They do not have tissues or organs. Almost all sponges have an internal skeleton. The skeleton is formed in the mesoglea and can be mineral (calcareous or silicic), horny (sponginous) or mixed (silicic-sponginous).

There are three types of sponge structure: ascon (asconoid), sicon (syconoid), leukon (leuconoid) (Fig. 1).

rice. one.
1 - ascon, 2 - sicon, 3 - leucon.

The most simply organized sponges of the asconoid type are in the form of a bag, which is attached to the substrate with its base, and the mouth (osculum) is turned upwards.

The outer layer of the sac wall is formed by integumentary cells (pinacocytes), the inner layer is formed by collar flagellar cells (choanocytes). Choanocytes perform the function of water filtration and phagocytosis.

Between the outer and inner layers there is a structureless mass - mesoglea, in which there are numerous cells, including those forming spicules (needles of the internal skeleton). The entire body of the sponge is permeated with thin canals leading to the central atrial cavity. Continuous work of choanocyte flagella creates a water flow: pores → pore channels → atrial cavity → osculum. The sponge feeds on those food particles that the water brings.

rice. 2.
1 - skeletal needles surrounding the mouth, 2 - atrial cavity,
3 - pinacocyte, 4 - choanocyte, 5 - stellate supporting cell,
6 - spicule, 7 - pore, 8 - amebocyte.

In sponges of the syconoid type, the mesoglea thickens and internal protrusions form, which look like pockets lined with flagellar cells (Fig. 2). The flow of water in the syconoid sponge is carried out along the following path: pores → pore channels → flagellar pockets → atrial cavity → osculum.

The most complex type of sponge is the leukone. Sponges of this type are characterized by a thick layer of mesoglea with many skeletal elements. The internal protrusions plunge deep into the mesoglea and take the form of flagellar chambers connected by efferent canals to the satria cavity. The atrial cavity in leuconoid sponges, as well as in syconoid sponges, is lined with pinacocytes. Leukonoid sponges usually form colonies with many mouths on the surface: in the form of crusts, plates, clods, bushes. The flow of water in the leuconoid sponge is carried out along the following path: pores → pore canals → flagellar chambers → efferent canals → atrial cavity → osculum.

Sponges have a very high ability to regenerate.

They reproduce asexually and sexually. Asexual reproduction is carried out in the form of external budding, internal budding, fragmentation, the formation of gemmules, etc. During sexual reproduction, a blastula develops from a fertilized egg, consisting of a single layer of cells with flagella (Fig. 3). Then some of the cells migrate inward and turn into amoeboid cells. After the larva settles to the bottom, the flagellar cells move inward, they become choanocytes, and the amoeboid cells come to the surface and turn into pinacocytes.

rice. 3.
1 - zygote, 2 - uniform crushing, 3 - coeloblastula,
4 - paranchymula in water, 5 - settled paranchymula
with bed inversion, 6 - young sponge.

Further, the larva turns into a young sponge. That is, the primary ectoderm (small flagellar cells) takes the place of the endoderm, and the endoderm takes the place of the ectoderm: the germ layers change places. On this basis, zoologists call sponges animals turned inside out (Enantiozoa).

The larva of most sponges is a parenchymula, in structure it almost completely corresponds to the hypothetical "phagocytella" of I.I. Mechnikov. In this regard, at present, the hypothesis of the origin of sponges from a phagocytella-like ancestor is considered the most reasonable.

Type Sponges are divided into classes: 1) Lime sponges, 2) Glass sponges, 3) Ordinary sponges.

Class Lime sponges (Calcispongiae, or Calcarea)

Marine solitary or colonial sponges with a calcareous skeleton. Skeletal needles can be three-, four- and uniaxial. The sicon belongs to this class (Fig. 2).

Class Glass sponges (Hyalospongia, or Hexactinellida)

Marine deep-sea sponges with a silicon skeleton consisting of six-axis spines. In a number of species, the needles are soldered, forming amphidisks or complex lattices.

Sponges are aquatic sessile multicellular animals. There are no real tissues and organs. They have no nervous system. The body in the form of a bag or glass consists of a variety of cells that perform various functions, and intercellular substance.

The body wall of sponges is permeated with numerous pores and channels coming from them, communicating with the internal cavity. The cavities and canals are lined with flagellated collar cells. With few exceptions, sponges have complex mineral or organic skeletons. Fossil remains of sponges are already known from Proterozoic rocks.

Lime and glass sponges:

1 - Polymastia corticata; 2 - sea ​​loaf sponge (Halichondria panicea); 3 - cup of Neptune (Poterion neptuni); 4 - Baikal sponge (Lubomirskia baikalensis);

5, 6 - Clathrina primordialis; 7 - Pheronema giganteum; 8 - Hyalonema sieboldi

About 5 thousand species of sponges have been described, most of them live in the seas. The type is divided into four classes: calcareous sponges, silicon-horn or ordinary, glass or six-ray sponges, and coral sponges. The latter class includes a small number of species that live in grottoes and tunnels among coral reefs and have a skeleton consisting of a massive calcareous base of calcium carbonate and flint uniaxial needles.

As an example, consider the structure of a lime sponge. Its body is sac-like, its base is attached to the substrate, and the hole, or mouth, is turned upwards. The paragastric region of the body communicates with the external environment by numerous channels, beginning with external pores.

In the body of an adult sponge, there are two layers of cells - ecto- and endo-dermis, between which lies a layer of structureless substance - mesoglea - with cells scattered in it. Mesoglea occupies most of the body, contains the skeleton and, among others, germ cells. The outer layer is formed by flat ectodermal cells, the inner layer is formed by collar cells - choanocytes, from the free end of which a long tick sticks out. Cells freely scattered in the mesoglea are divided into immobile - stellate, performing a supporting function (collencites), skeletal mobile (scleroblasts), engaged in the digestion of food (amoebocytes), reserve amoeboid, which can turn into any of the above types, and sexual. The ability of cellular elements to pass into each other indicates the absence of differentiated tissues.

According to the structure of the body wall and the canal system, as well as the location of the sections of the flagellar layer, three types of sponges are distinguished, the simplest of which is the ascon and the more complex ones, the sicon and leukon.

Various types of sponge structure and their channel system:

BUT - ascon; B - sikon; AT - leucon. The arrows show the flow of water in the body of the sponge.

The sponge skeleton is formed in the mesoglea. The mineral (calcareous or siliceous) skeleton consists of separate or soldered needles (spicules) that form inside scleroblast cells. The organic (spongin) skeleton is composed of a network of fibers that are similar in chemical composition to silk and are formed intercellularly.

Sponges are filtrate organisms. Through their body there is a continuous flow of water, caused by the action of collar cells, the flagella of which beat in one direction - towards the paragastric cavity. Collar cells capture food particles (bacteria, unicellular, etc.) from the water passing by them and swallow them. Part of the food is digested on the spot, part is transferred to amoebocytes. Filtered water is ejected from the paragastric cavity through the mouth.

Sponges reproduce both asexually (by budding) and sexually. Most sponges are hermaphrodites. Sex cells lie in the mesoglea. Spermatozoa enter the canals, are excreted through the mouth, penetrate into other sponges and fertilize their eggs. The zygote cleaves, resulting in a blastula. In non-calcareous and some calcareous sponges, the blastula consists of more or less identical flagellar cells (coeloblastula).

In the future, part of the cells, losing flagella, plunges inward, filling the cavity of the blastula, and as a result, a larva-parenchymula appears.

More often, sponges live in colonies resulting from incomplete budding. Only a few sponges are solitary. There are also secondary single organisms. Their importance in the life of reservoirs is very great. By filtering through their body a huge amount of water, they help to cleanse it of impurities from solid particles.

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Sponges are a type of aquatic predominantly marine immobile primitive animals. In terms of the complexity of their structure, they occupy an intermediate position between colonial protozoa and coelenterates. Usually they are not studied in a school biology course, although in terms of the number of species (about 8 thousand), this is a fairly large group.

Previously, a person used sponges in everyday life (as washcloths).

Now we have learned how to make artificial sponges, but from them you can get an idea of ​​\u200b\u200bhow animal sponges are arranged. Their distinctive feature is the porous structure of the body, capable of passing a large amount of water through itself.

In the body of sponges there are different cells that perform different functions and differ from each other in their structure. On this basis, sponges differ from colonial protozoa. However, sponge cells are weakly interconnected, do not fully lose their ability to be independent, are almost not controlled together, and do not form organs.

Therefore, it is believed that sponges do not have tissues. In addition, they do not have true nerve and muscle cells.

The shape of the body of sponges is different: similar to a bowl, a tree, etc. At the same time, all sponges have a central cavity with a fairly large hole (mouth) through which water exits. The sponge sucks in water through smaller holes (tubules) in its body.

The figure above shows three options for the structure of the sponge aquifer system.

In the first case, water is sucked into a common large cavity through narrow side channels. In this common cavity, nutrients are filtered from the water (microorganisms, organic residues; some sponges are predators and are able to capture animals). Catching food and the flow of water is carried out by the cells depicted in red in the figure. In the figure in the second and third cases, the sponges have a more complex structure.

There is a system of channels and small cavities, the inner walls of which form the cells responsible for nutrition. The first variant of the structure of the body of a sponge is called ascon, second - Seacon, the third - leukone.

Cells shown in red are called choanocytes.

They have a cylindrical shape, a flagellum facing the chamber-cavity. They also have a so-called plasma collar, which traps food particles. Choanocyte flagella push water in one direction.

Sponges have a number of other cell types.

The diagram above shows part of the ascon's body. Integumentary cells are marked in yellow ( pinacocytes). They perform a protective function. Between choanocytes and pinacocytes there is a rather powerful layer mesohyl(shown in grey). It has a non-cellular structure, it is a fibrous gelatinous substance in which all other types of cells and various formations are located.

archeocytes(light green cell in the diagram) - are amoeba-like mobile undifferentiated cells that can turn into all others. When a sponge loses a body part, it is thanks to the division and differentiation of archeocytes that the process of regeneration occurs.

Article: The concept of a sponge

Also, archeocytes perform the function of transporting substances between cells (for example, from choanocytes to pinacocytes). There are also many other types of cells in the mesohyl (sex cells, nutrient-containing cells, collagen, etc.). Also in the mesochile there are needles that perform a supporting skeletal function, they allow the sponge to keep its shape. The needles have a crystalline structure.

Sponges reproduce both asexually and sexually. Asexual reproduction is carried out by budding.

Daughter individuals may remain attached to the parent. As a result, colonies are formed. During sexual reproduction, spermatozoa from one sponge enter the channels and chambers of another. Fertilization of eggs (oocytes) occurs. The resulting zygote begins to divide, a larva is formed, which leaves the mother's body with a current of water and subsequently settles in a new place. In its structure, the larva does not have germ layers, but resembles a colony of unicellular flagellates.

The larva does not swim passively, but with the help of flagella. After settling in a new place, it twists so that the flagella turn inward, and the larva begins to grow, turning into a sponge.

SPONGE (Spongia, Porifera) - a type of multicellular invertebrate aquatic animals. G. is characterized by cellular differentiation with little intercellular coordination, as a result of which the individual cells of the body are practically independent of each other.

G.'s body consists of ento- and ectoderm and a gelatinous substance lying between them - mesoglia; muscle and nerve cells characteristic of higher animals are absent. G.'s skeleton consists of calcareous or silica formations of different size and shape - spicules, in some types of G. - from organic matter (spongin).

Water is constantly filtered through channels that run inside the body and are lined from the inside with a layer of ectodermal flagellar cells (choanocytes).

Various microorganisms (protozoa, bacteria, algae, etc.), as well as particles of detritus that enter the body with the flow of water, are captured by cells and digested in them.

Some of the freshwater G. (for example, bodyagi) play an important role in the natural purification of water bodies, but at the same time, settling in various hydraulic structures and clogging them, they can also cause significant harm.

In total there are approx. 5000 types of G.; in the northern and Far Eastern seas within the USSR lives approx.

300 species, in the Black Sea - approx. 30, in the Caspian - 1 species. Freshwater G. in the USSR are represented by Baikal species of G. and several types of bodyag.

The practical value of sponges is small. Toilet, or Greek, G. serves as an object of fishing in the Mediterranean and some other seas; it is sometimes used in dried and purified form in surgery instead of cotton wool. Dried bodyaga in folk medicine is used as a treatment. remedy for rheumatism, as well as a cosmetic.

D. N. Zasukhin.

Biology and lifestyle of sponges

Sponges are exclusively aquatic animals that lead a stationary lifestyle, like many plants.

They firmly establish themselves on some solid substrate, and do not leave their "familiar place" of their own free will. These are such primitive organisms that they have no ability to move independently on the ground or in the water column.

The immobile lifestyle of sponges is due to the fact that sponges do not have an organized muscular and nervous system, since the cells that make up their body are differentiated and are not able to act "collectively".
The rudimentary ability to respond to strong stimuli in them is associated with the contraction of myocytes or protoplasm of epithelial and mesogley cells, while each cell responds to irritation independently.

Experiments aimed at studying the ability of sponges to respond to external stimuli have shown that this reaction is extremely slow.

So, sponges living in shallow water are able to close the mouth (during low tide) in three minutes, and fully open it in 7-10 minutes.

In addition to the ability to contract, some sponge cells (in particular, amoebocytes) are able to move slowly with the help of pseudopodia and prolegs in the thickness of the mesoglea.

The inability of sponges to move parts of their body would have a negative impact on their viability - after all, for a normal existence, sponges need a watercourse that brings food, gases through the channels to the cells of the body and carries away waste products. In stagnant water, sponges would not be able to develop and exist normally if it were not for choanocytes. These cells are located along the channels and chambers passing through the porous body of the sponge, and are equipped with movable flagella that are in constant motion.

Sponges - description, types, signs, nutrition, examples and classification

It is the flagella of choanocytes that create the necessary flow of water through the body of the animal.
If a dye is injected into the body of an aquarium sponge with a syringe, then after a while a cloud of colored water will appear from the mouth.

sponge breath

Like all aquatic animals, sponges use oxygen dissolved in water for breathing.

As a result of oxidative processes, sponges release carbon dioxide, which must be removed from the cells into the external environment. Gas exchange occurs during the flow of water through the channels and flagellar chambers, while the cells of the mesoglea, located near the watercourse, capture oxygen, give off waste products. Since many of the cells in the mesoglea are mobile and the mesoglea itself has the appearance of a jelly, the cells in it mix slowly, and most of them are able to receive food and remove waste.

A certain role in supplying cells with oxygen and removing carbon dioxide is played by microscopic algae that enter the channels and pores of sponges with water and live there for some time. In this case, a symbiotic relationship is observed between sponges and phytoalgae.

Nutrition and excretion of sponges

The watercourse contributes not only to gas exchange, but also to the cells of the sponges receiving nutrients and mineral salts necessary for normal life.

Since the cells of sponges are differentiated, there is no need to talk about the existence of any, even a rudimentary, digestive system in these animals. Each cell of the body independently extracts everything necessary from the water, and releases everything unnecessary into the water. We can say that the level of physiology of sponges in this respect resembles the physiology of unicellular organisms.

Sponges are fed by organic microparticles that are in suspension in water - the remains of microscopic animals and plants, unicellular organisms.

The particles enter the canals and flagellar chambers with the help of the same choanocytes, then they are captured by mobile amoebocytes and spread throughout the mesoglea. At the same time, the amoebocytes release the pseudopod, envelop the particle, and draw it into the cell.

A vacuole appears in the pseudopod - a bubble filled with a medium capable of dissolving and digesting organic matter. The particle dissolves, and grains of a fat-like substance appear on the surface of the vacuole.

If the nutrient particle is too large to be digested by one amoebocyte, a group of amoebocytes comes into play - they surround the particle from all sides and digest it together. The structure of choanocytes in some types of sponges allows them to also take part in the digestion of food.

Sponges pass through their pores, channels and flagellar chambers everything that is contained in the water, including inedible particles. At the same time, amoebocytes capture both organic matter and that which cannot be digested in the vacuole.

Undigested food residues and indigestible contents are released into the mesoglea and gradually move to the walls of the canals, from where they are expelled by choanocyte flagella into the external environment through the atrial cavity and mouth.

How long do sponges live?

Sponge Type (Porifera, or Spongia)

The structure and classes of sponges

Sponges are ancient primitive multicellular animals. They live in marine, less often fresh water bodies. They lead a fixed lifestyle. They are filter feeders. Most species form colonies. They do not have tissues or organs. Almost all sponges have an internal skeleton. The skeleton is formed in the mesoglea and can be mineral (calcareous or silicic), horny (sponginous) or mixed (silicic-sponginous).

There are three types of sponge structure: ascon (asconoid), sicon (syconoid), leukon (leuconoid) (Fig. 1).

rice. one.

Different types of sponge structure:
1 - ascon, 2 - sicon, 3 - leucon.

The most simply organized sponges of the asconoid type are in the form of a bag, which is attached to the substrate with its base, and the mouth (osculum) is turned upwards.

The outer layer of the sac wall is formed by integumentary cells (pinacocytes), the inner layer is formed by collar flagellar cells (choanocytes).

Choanocytes perform the function of water filtration and phagocytosis.

Between the outer and inner layers there is a structureless mass - mesoglea, in which there are numerous cells, including those forming spicules (needles of the internal skeleton). The entire body of the sponge is permeated with thin canals leading to the central atrial cavity. Continuous work of choanocyte flagella creates a water flow: pores → pore channels → atrial cavity → osculum.

The sponge feeds on those food particles that the water brings.

rice. 2. The structure of the sycon (Sycon sp.):
1 - skeletal needles surrounding the mouth, 2 - atrial cavity,
3 - pinacocyte, 4 - choanocyte, 5 - stellate supporting cell,
6 - spicule, 7 - pore, 8 - amebocyte.

In sponges of the syconoid type, the mesoglea thickens and internal protrusions form, which look like pockets lined with flagellar cells (Fig. 2).

The flow of water in the syconoid sponge is carried out along the following path: pores → pore channels → flagellar pockets → atrial cavity → osculum.

The most complex type of sponge is the leukone.

Sponges of this type are characterized by a thick layer of mesoglea with many skeletal elements. The internal protrusions plunge deep into the mesoglea and take the form of flagellar chambers connected by efferent canals to the satria cavity. The atrial cavity in leuconoid sponges, as well as in syconoid sponges, is lined with pinacocytes.

Leukonoid sponges usually form colonies with many mouths on the surface: in the form of crusts, plates, clods, bushes. The flow of water in the leuconoid sponge is carried out along the following path: pores → pore canals → flagellar chambers → efferent canals → atrial cavity → osculum.

Sponges have a very high ability to regenerate.

They reproduce asexually and sexually.

Asexual reproduction is carried out in the form of external budding, internal budding, fragmentation, the formation of gemmules, etc. During sexual reproduction, a blastula develops from a fertilized egg, consisting of a single layer of cells with flagella (Fig. 3).

Then some of the cells migrate inward and turn into amoeboid cells. After the larva settles to the bottom, the flagellar cells move inward, they become choanocytes, and the amoeboid cells come to the surface and turn into pinacocytes.

Development of the lime sponge (Clathrina sp.):
1 - zygote, 2 - uniform crushing, 3 - coeloblastula,
4 - paranchymula in water, 5 - settled paranchymula
with bed inversion, 6 - young sponge.

That is, the primary ectoderm (small flagellar cells) takes the place of the endoderm, and the endoderm takes the place of the ectoderm: the germ layers change places. On this basis, zoologists call sponges animals turned inside out (Enantiozoa).

The larva of most sponges is a parenchymula, in structure it almost completely corresponds to the hypothetical "phagocytella" of I.I. Mechnikov.

In this regard, at present, the hypothesis of the origin of sponges from a phagocytella-like ancestor is considered the most reasonable.

Type Sponges are divided into classes: 1) Lime sponges, 2) Glass sponges, 3) Ordinary sponges.

Class Lime sponges (Calcispongiae, or Calcarea)

Marine solitary or colonial sponges with a calcareous skeleton.

Skeletal needles can be three-, four- and uniaxial. The sicon belongs to this class (Fig. 2).

Class Glass sponges (Hyalospongia, or Hexactinellida)

Marine deep-sea sponges with a silicon skeleton consisting of six-axis spines. In a number of species, the needles are soldered, forming amphidisks or complex lattices.

The skeletons of some species are very beautiful and are used as collectibles and souvenirs.

Representatives: basket of Venus (Fig. 4), hyalonema.

Class Ordinary sponges (Demospongiae)

This class includes the vast majority of modern types of sponges.

The skeleton is silicon combined with spongy filaments. In some species, silicon needles are reduced, leaving only spongy filaments.

Silicon needles - four- or uniaxial. Representatives: toilet sponge (Fig. 5), Neptune's cup (Fig. 6), badyaga, living in fresh water.

rice. 4.

Basket of Venus
(Euplectella asper)
fig.5. toilet sponge
(Spongia officianalis)
rice. 6.

Neptune Cup
(Poterion neptuni)

Training tasks. Invertebrates

Level A tasks

Choose one correct answer from the four given

A1. Sponges are characterized

Systematic sponges are based on

A3. The intestines are characterized

A5. body cavity

Level B assignments

Choose three correct answers from the six given

The following characteristic features of the lifestyle of sponges are known

3) depending on the conditions, sponges of the same species may differ in body shape

4) all sponges live in both sea and fresh water

6) sponges live for several thousand years

IN 2. In the outer layer of the body of the hydra are cells

2) stinging

4) nervous

5) intermediate

1) they have special suction cups or hooks

4) during reproduction, a large number of eggs are formed, live birth and alternation of generations are characteristic

6) in the process of evolution they had a loss of the nervous system

AT 4. The mantle cavity of mollusks is a cavity

1) into which the anal, genital and excretory openings open

4) in which the respiratory and chemical sense organs are located

5) between the mantle and the body of the mollusk

Match the contents of the first and second columns

AT 5. Set the correspondence between classes and taps Mollusks and Echinoderms

CLASSES TYPES

A) sea lilies 1) Shellfish

B) starfish 2) Echinoderms

B) gastropods

D) sea urchins

D) bivalve

E) Ophiurs

G) Holothurians

H) Cephalopods

Establish a correspondence between some orders of insects and the type of their mouth apparatus.

INSECT ORDER MOUTH TYPE

A) cockroach 1) sucking

B) Orthoptera 2) gnawing

B) Coleoptera

D) Dragonflies

E) butterflies

Set the correct sequence of biological processes, phenomena, practical actions

B8. Establish the sequence of stages of butterfly development

1) adult insect

3) caterpillar

4) chrysalis

Set the sequence of events for the rosin of bees

Sponges are so unlike other multicellular animals that for a long time they were considered representatives of a special group of "zoophytes", that is, animal-plants. Indeed, they lead an attached lifestyle, are unable to make active movements, they lack a nervous system and sensory organs. In addition, some of their representatives may have a green color, since algae settle in their cells.

About 9 thousand species of these amazing creatures are known, distributed in the seas and fresh waters.

For the first time, the structure and vital processes of sponges were studied in detail by R. E. Grant, who proposed the scientific name of this group of animals.

Structural features of sponges. Among the sponges there are single forms, but most species form colonies, the size of which can reach 2 m. Colonies of sponges in their shape can resemble bushes, cortical growths, lumps, etc., overgrowing various surfaces. The color is also varied - yellow, brown, white, red, purple or green.

There is evidence that giant sponges live on the surface of containers with spent nuclear fuel buried on the seabed.

Various species are found in fresh water badyag. Their colonies often form around submerged objects. In stagnant water bodies, they have the shape of a bush, in flowing water bodies they look like cortical fouling. The color of the colony is gray or dirty green.

The body of a goblet-shaped sponge (Fig. 58, 1). With their lower part, animals are attached to underwater objects. With the help of special video filming, it was established that some sponges can move due to amoeboid cells. But even the fastest of them do not cover a distance of more than 1 mm per day.

At the opposite - upper - end of the body of the sponge is a hole. But it's not a mouth. If rubbed dry ink is poured into an aquarium with sponges, then its particles will first go to the body of the sponge, then through the tubules in the walls of the body they will get inside and, in the end, will be removed through the hole at the upper end of the body.

Thus, this hole does not serve to absorb food, but to remove water from the body with its undigested residues.

The body of a sponge is made up of cells of different types. But they do not form tissues. Each cell functions independently.

outer layer the bodies of sponges form cells that resemble the cells of the integumentary epithelium of other multicellular animals. Among the cells of the outer layer, there are those that have a pore. These pores begin a system of tubules penetrating the walls of the body. The openings of these tubules are surrounded by cells capable of contracting and closing them. The tubules conduct water with food particles to the internal cavity. This cavity is usually lined with special cells with flagella, the base of which is surrounded by a membranous collar. (Fig. 58, 2). Such cells form the inner layer. In many sponges, they are located inside the walls of the body, forming flagellar chambers. The work of the flagella ensures the movement of water through the system of tubules and the internal cavity.

Between the outer and inner layers of cells is intercellular substance containing different types of cells. Some of them form internal skeleton of sponges.

Another cell type amoeboid. These cells, with the help of false legs, capture food particles that are digested in their digestive vacuoles. Moving along the body of the sponge, amoeboid cells distribute nutrients. material from the site

In large vacuoles of special cells of many species of sponges that live at shallow depths with sufficient illumination, special types of cyanobacteria settle. These prokaryotes can make up to 50% of the cell mass of the sponge itself. They supply oxygen and synthesized organic substances, and receive from animals the carbon dioxide necessary for photosynthesis and protection from enemies.

The structure of sponges is characterized by the following features:

• they do not have real tissues, but only cells of different types;
• the body is goblet, usually fixedly attached to underwater objects;
• in the walls of the body there is a system of tubules, inside there is a cavity that communicates with the environment through a hole at the top of the body;
• the movement of water through the body of sponges is provided by collar cells with flagella;
• in the walls of the body there is a skeleton of inorganic or organic substances;

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